<!--
  # 本模块仅作为网页摄像头技术验证
  # 应整合到Content.vue【已整合 2024-4-22】
  # 最后编译时间 2024-05-08
  # 存在问题【暂无】
-->
<template>
    <div class="camera_outer">
      <video id="videoCamera" :width="videoWidth" :height="videoHeight" autoplay></video>
      <canvas style="display:none;" id="canvasCamera" :width="videoWidth" :height="videoHeight" ></canvas>
      <div v-if="imgSrc" class="img_bg_camera">
        <img :src="imgSrc" alt="" class="tx_img">
      </div>
      <el-button @click="getCompetence()">打开摄像头</el-button>
      <el-button @click="stopNavigator()">关闭摄像头</el-button>
      <el-button @click="setImage()">拍照</el-button>
    </div>
  </template>
  <script>
  export default {
    data() {
      return {
          videoWidth: 800,
          videoHeight: 300,
          imgSrc: '',
          thisCancas: null,
          thisContext: null,
          thisVideo: null,
      };
    },
    created() {},
    methods: {
      getCompetence () {
        var _this = this
        this.thisCancas = document.getElementById('canvasCamera')
        this.thisContext = this.thisCancas.getContext('2d')
        this.thisVideo = document.getElementById('videoCamera')
        // 旧版本浏览器可能根本不支持mediaDevices，我们首先设置一个空对象
        if (navigator.mediaDevices === undefined) {
          navigator.mediaDevices = {}
        }
        // 一些浏览器实现了部分mediaDevices，我们不能只分配一个对象
        // 使用getUserMedia，因为它会覆盖现有的属性。
        // 这里，如果缺少getUserMedia属性，就添加它。
        if (navigator.mediaDevices.getUserMedia === undefined) {
          navigator.mediaDevices.getUserMedia = function (constraints) {
            // 首先获取现存的getUserMedia(如果存在)
            var getUserMedia = navigator.webkitGetUserMedia || navigator.mozGetUserMedia || navigator.getUserMedia
            // 有些浏览器不支持，会返回错误信息
            // 保持接口一致
            if (!getUserMedia) {
              return Promise.reject(new Error('getUserMedia is not implemented in this browser'))
            }
            // 否则，使用Promise将调用包装到旧的navigator.getUserMedia
            return new Promise(function (resolve, reject) {
              getUserMedia.call(navigator, constraints, resolve, reject)
            })
          }
        }
        var constraints = { audio: false, video: { width: this.videoWidth, height: this.videoHeight, transform: 'scaleX(-1)' } }
        navigator.mediaDevices.getUserMedia(constraints).then(function (stream) {
          // 旧的浏览器可能没有srcObject
          if ('srcObject' in _this.thisVideo) {
            _this.thisVideo.srcObject = stream
          } else {
            // 避免在新的浏览器中使用它，因为它正在被弃用。
            _this.thisVideo.src = window.URL.createObjectURL(stream)
          }
          _this.thisVideo.onloadedmetadata = function (e) {
            _this.thisVideo.play()
          }
        }).catch(err => {
          console.log(err)
        })
      },
      //  绘制图片（拍照功能）
      setImage () {
        var _this = this
        // 点击，canvas画图
        _this.thisContext.drawImage(_this.thisVideo, 0, 0, _this.videoWidth, _this.videoHeight)
        // 获取图片base64链接
        var image = this.thisCancas.toDataURL('image/png')
        _this.imgSrc = image
        this.$emit('refreshDataList', this.imgSrc)
      },
      // base64转文件
      dataURLtoFile (dataurl, filename) {
        var arr = dataurl.split(',')
        var mime = arr[0].match(/:(.*?);/)[1]
        var bstr = atob(arr[1])
        var n = bstr.length
        var u8arr = new Uint8Array(n)
        while (n--) {
          u8arr[n] = bstr.charCodeAt(n)
        }
        return new File([u8arr], filename, { type: mime })
      },
      // 关闭摄像头
      stopNavigator () {
        this.thisVideo.srcObject.getTracks()[0].stop()
      }
    }
  };
  </script>
  <style scoped>
  .dashboard-container {
    width: 100%;
    height: 100%;
    color: #fff;
  }
  .tx_img {
    max-width: 100%;
  }
  </style>
  